Pressure treatment of electroscopic toners is an efficient way of fixing them to substrate sheets such as paper. It is inexpensive in equipment required, uses small quantities of power and can be effected at high speeds. Detailed information with regard to this process as carried out in connection with sheets of ordinary width is found in a copending patent application of Brenneman et al., Ser. No. 340,600 filed Mar. 12, 1973.
The pressures required in connection with this type of fixing vary in accordance with the properties of the toner used and the rolls used in applying the pressure may be loaded in varying degrees to accommodate these toner variations. As a practical matter this loading is usually found to lie somewhere in a range of 200 to 500 pounds per lineal inch of roll length (pli).
One of the problems associated with pressure fixing is the design of equipment which is able to withstand these loadings for long periods without mechanical breakdown, so that any arrangement which allows the use of a lower pressure with any particular toner contributes to a more reliable and service-free construction.